Two Beers, Cetirizine, and a Three-Mile Ride
It is 11 p.m. You weigh about 170 lb. Over the past three hours you had two 12-ounce beers with dinner, and about an hour ago you took a 10 mg cetirizine tablet for allergies. You feel alert but your eyes are scratchy and you yawned twice in the last ten minutes. You have a 3-mile ride home on surface streets with two left turns and a poorly lit intersection. Your motorcycle is a 300 cc naked bike with ABS. You have a helmet, gloves, and jacket. A friend at the restaurant offers to drive you home in her car; you can pick up the bike tomorrow. You are 22 years old. You have no other medications and no history of alcohol problems.
1. Should you ride home? Explain the impairment factors beyond the two beers.
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No. Two 12-ounce beers over three hours at 170 lb is likely a low BAC, but cetirizine is a sedating antihistamine and you are already yawning with scratchy eyes. Add 11 p.m. darkness, a poorly lit intersection, and two left turns, and your margin is gone. Alcohol and sedating medication can multiply each other even when each alone feels mild. Guam's DUI law is not only a number; an officer can arrest on driving impairment. You do not need to feel drunk to be unsafe. Accept the ride.
2. Estimate whether you are under Guam's adult legal limit. Does that settle the decision?
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A rough estimate for two standard drinks over three hours at 170 lb is under 0.08, but that is not a decision. You do not know the actual alcohol content, pour size, or how fast you absorbed it, and food and hydration change the curve. Cetirizine adds drowsiness that a BAC number does not capture. Guam's adult per se limit is 0.08, but impairment can be charged below it. The legal question and the safety question both point the same way: do not ride.
3. What should you do with the bike and keys, and how would you answer a friend who says 'two beers is nothing'?
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Give your friend the keys or put them away, lock the bike, and leave it. Pick it up tomorrow after sleep and after the cetirizine has worn off. Tell your friend that 'two beers' is only part of the story: the medication, the hour, and the yawning are all impairment factors. If a friend insists on riding after drinking or sedating medication, take the keys, call a ride, or involve someone sober. The cost of leaving the bike overnight is small compared with a crash.